Pyrolysis of chloro-fluoro alkanes



Patented May 8, 1951 'UNlTED SES PYROLYSIS OF CHLORO-FLUORO ALKANES NDrawing. Application November 30, 1945,

Serial No. 632,116

13 Claims.

This is a continuation-in-part of our earlier filed applications SerialNo. 435,064, now Patent No. 2,387,247, and Serial No. 475,526, filedFebruary 11, 1943.

This invention relates to the preparation of organic fluorine compoundsby pyrolysis. By pyrolysis, we mean the transformation of a compoundinto another substance or other substances through the agency of heatalone. (Hurd, The Pyrolysis of Carbon Compounds, p. 9) The termpyrolysis used in this specification therefore will include not only thedecomposition of compounds but also the making of more complexcompounds. In the applications identified as Benning et al., Serial No.344,666, filed July 10, 1940, now Patent No. 2,365,516, and BenningSerial No. 379,473, filed February 18, 1941, now Patent No. 2,343,252,are disclosed two processes involving a reaction between afluoro-hydrocarbon and HCl in the presence of a catalyst. Thosereactions may be described as additive, since their apparent course isthe addition of HCl to the olefine in the place of double bonds. Thesereactions were carried out at comparatively low temperatures, in mostcases below 350 0., because those temperatures were satisfactory andbecause observations of a limited number of experiments at highertemperatures showed the existence of what were thought to be undesirableside reactions. We have now discovered that the side reactions arepyrolytic and of a fundamentally difierent nature than HCl addition, andthat they and other reactions that occur at elevated temperatures can beput to valuable use.

It is an object of this invention to produce organic compounds bypyrolysis. Another object of the invention is to produce compounds whichare useful, by methods which are economically and technicallysatisfactory. Another object of the invention is to produce new fluorohydrocarbons. A particular object of the invention is to synthesizeorganic compounds having fiuoroalkyl chains by the pyrolysis offluorohalogeno carbon compounds. Another object of the invention is toproduce the compound CF2=CF2 by methods which are technically andeconomically satisfactory.

According to our invention iluoro-chloro alkanes, which may otherwise becalled fluorochloro saturated aliphatic compounds, are made into othercompounds by pyrolysis. This reaction may be carried out in isolation,or in the presence of a catalyst, by which we mean a substance thataifects the result without combining withthe reactants. Inert gases suchas dehydrochlorination predominates.

hydrogen, or chlorine, substituents. Fluorochloro-alkanes, containing atleast one displaceable hydrogen, are preferred as starting materials.Among the particular materials that have been pyrolyzed by the processof this invention are those recited in the examples given hereinafter inextenso, and CHzClF, CH3CC12F, CHzClCClFz, C2HC12F3 and CClzFCClFz.Differences have been observed in the efiect of pyrolysis on saturatedand unsaturated compounds.

When fluoro-chloro-alkanes, containing one or more displaceable hydrogenatoms, are pyrolyzed,

Such dehydrochlorination may be intermolecular or intramolecular,depending upon the relative positions of the hydrogen and chlorine atomsin the molecule. Where the hydrogen and chlorine atoms are on a singlecarbon, the reaction appears to involve primarily an intermoleculardehydrochlorination, wherein the elements of the hydrogen chloride areobtained from difierent molecules, to produce free radicals whichcondense to form compounds of higher molecular weights. For example,when Cl-IClFz is pyrolyzed, one molecule may lose a hydrogen and anothermay lose a chlorine to form the free radicals CC1F2 and CI-IF2, whichradicals may further pyrolyze to the free radical =CF2. Such freeradicals condense to form compounds of higher molecular weight,represented by CF2=CF2, CClFzC'HFz, C4Fs and the compounds of the seriesH(CF2)nCl in which n is at least 3 with the compounds of increasingmolecular weight being produced in diminishing propor-' tions. Thecompounds of the formula H(CF'2)1LC1 are open chain compounds with the Hand C1 atoms on opposite terminal carbon atoms and they may berepresented more accurately by the formula HCF2(CF2) nCFZC]. where nrepresents at least one.

Where the hydrogen and chlorine atoms are on adjacent carbon atoms, thereaction appears to involve primarily an intramoleculardehydrochlorination, wherein both elements of the hydrogen chloride areobtained from the same molecule, to produce fluoro-olefines which have atendency to polymerize. For example, the pyrolysis of CClFzCHFz producesprimarily C2F4 and C4F8, octafluorocyclobutane.

Where the hydrogen and chlorine atoms are on different non-adjacentcarbon atoms, the reaction appears to involve both an intermoleculardehydrochlorination and a splitting of the molecule to produce compoundsof lower molecular weight. For example, the pyrolysis of compounds ofthe formula H(CF2)11.C1 produces C2F4 and the other lower members of theseries mormcl. Where the fiuoro-chloro-alkane contains no hydrogen, thepyrolysis may result in a disproportionation, as for example in thepyrolysis of CClzFz which produces CFi and CFsCl along with otherproducts. In the case of compounds hav-' ing more than one carbonatom,cleavagemay result, followed by reproportionation of the halogen amongthe fragments e. g. CF2C1CF2'C1 yields CF2C12 and CF3C1 among otherproducts.

The preferred starting materials of our inven-'- tion are thehydrogen-containing fluoro-chloro alkanes in which the H and Cl atomsare on a single carbon, and particularly 'CHClFz. The next mostpreferred starting materials are the hydrogen-containingfiuoro-chloro-alkanes having H and Cl atoms on adjacent carbons.vAlthough for the production of particular compounds the reaction willbe carried out under well-controlled conditions of time, temperature andpressure, complex mixtures of compounds of various molecular weights canbe produced by subjecting the compounds to pyrolytic conditions forextended periods of time. Pressures may also be used to vary theresults, although for the purposes of economy and safety each particularreaction should be carried out with the lowest pressure consistent withoptimum results. For example, pressures of four atmospheres absolutehave been found satisfactory in many cases. In general, operations maybe carried out at pressures between 0.1 and atmospheres absolute, butother pressures are useful and may be employed when an increase inefficiency will result.

This is a pyrolytic process. The disintegration and integration areproduced essentially by heat. It is, therefore, important to select atemperature which will efliciently produce the reaction. The temperatureshould be selected to give optimum production of the desired product. Wehave found that excellent pyrolytic results have been produced attemperatures between 600 and 1000 C., but that particular substanceshave been pyrolyzed at temperatures as low as 400 C. and above 1000 C.under appropriate conditions of time and pressure. Electrical heating isefficient, but any method of heating may be applied. The temperatureswhich are used must also be chosen in view of the materials that composethe re- .action apparatus.

The time of exposure of the reactants to the pyrolytic conditions is amatter of considerable importance where a particular product is desired.Extending the period of exposure frequently produces compounds ofincreased molecular weight.

In general, the pyrolysis proceeds to the integration of new fluorohydrocarbons efiiciently in the absence of catalysts. Catalysts aregenerally useful in altering the course of the pyrolysis by splittingoff more fluorine, rather than in improving its efiiciency. Heavy metalhalides and halides of the alkaline earth metals, such as BaClz andCaClz have been used.

The process is preferably carried out continuously by passing theconvertible material through a tube heated to a pyrolytically effectivetemperature. The tube should be composed of a material which is inert tothe reaction and the reaction products. Carbon and the noble metals aresufliciently inert and have proved to be satisfactory materials for theconstruction of reaction chambers. The chamber need not be whollycomposed of the inert material, but may be lined with it. Reactionchambers containing a platinum lining are particularly satisfactory. Theprocess may be carried out in batches rather than continuously, butcontinuity is preferred.

The following examples have been carried out and have been selected forinclusion in this specification because they show a number of thecompounds which have been successfully pyrolyzed, and a number ofclasses thereof, and a variety of reaction conditions. The applicantspresent these examples, not as constituting any limitation of the workwhich has actually been done, but as sufficiently representative toenable persons skilled in the art to practice the invention. In theseexamples the terms conversion and amount converted include theassumption that the disappearance of one mol of the primary organicmaterial resulted in the liberation of one mol of halogen acid. Thisassumption is warranted by the close agreement between the figures forconversion obtained by acid analysis and the actual primary materialwhich disappeared. Unless otherwise noted, the examples were carried outat a pressure of about one at-' mosphe're. The temperatures of thepyrolyses were measured with a thermocouple which was placed in contactwith the outer surface of the reaction tube near the center of theheated zone, so that the true average temperature of the gases in thetube may have been somewhat lower than the values given.

Example I One hundred eighty grams of CHClF'z were passed through asilver tube 8.0 mm. I. D. x 700 mm. long at a rate of about g./hr. whilethe pressure in the tube was kept at approximately one atmosphere abs.The tube temperature was maintained at about 700 C. over an estimatedlength of 200 mm. by electrical heating. The reaction products werewashed with water, dried and condensed in receivers cooled to about 70"C. The crude organic products (156 g.) were This was equivalent to adisappearance of 28% of the CHClFa fed and a yield of C2F4 therefrom of83%.- Analysis of the washwater for acid indicated that a conversion of27% had taken place.-

Eaidmple II CHClFz was thermally decomposed in an ap paratus similar tothat described in nxampie I while being maintained at a ressure or 4atrii. absolute. The organic flow rate was about 387 g./hr and theoperating temperature about 700 C. A conversion of 23% was obtainedunder these conditions. The acid free organic products Example IIICHClFz containing 2.7 wt. per cent CHChF was passed through a tube whichwas made of base metal resistant to oxidation at high temperatures andlined with a thin layer of platinum. The flow rate was such that aconversion of about 24% was obtained, while the tube temperature wasmaintained at about 700 C. The reaction products were analyzed, afterremoval of acid constituents, and found to contain almost nothing elsebut 02F; and the starting components.

Example IV CHCIF2 was passed over a catalyst of activated carboncontained in a nickel jacketed carbon tube, 18.8 mm. I. D. x 600 mm.long. The tube was heated to about 300 C. and the-flow of CHClFzmaintained at about 55 g./hr. Under these conditions a 3.5% conversionto other products was obtained as determined by acid analysis. Thiscompares with a conversion of about 1% which was obtained at 525 C. inthe absence of any catalyst.

Example V CI-IClFz was passed over a catalyst consisting of iron andiron halides formed during pyrolysis contained in a nickel jacketedgraphite tube which was heated to about 675 C. The CI-IClFz flow ratewas such that a conversion of 24% was obtained. Under these conditions,13 mole per cent of the acid formed was HF. The thermal decomposition ofCHClFz under similar conditions in the absence of a catalyst resulted inthe formation of less than 5 mole per cent H35 in the acid evolved.

Example VI The thermal decomposition of CHClFz in the presence of acatalyst consisting of deoxidized copper and copper halides formedduring pyrolysis was carried out in a manner similar to that describedin Example V. The results obtained were also similar, the HF content ofthe acid being raised from less than 5 mole per cent to about 13 moleper cent upon introduction of the catalyst into the graphite tube.

7 Example VII 'CI-IClFz was passed over a catalyst contained in a nickeljacketed graphite tube heated to about 620 C. The catalyst consisted ofan alloy made up of 58% Ni, 20% Fe, 20% Mo and 2% Mn and any of thecorresponding metal halides 6 formed during the pyrolysis. The CHCIFZflow rate was such that a conversion of 25% was obtained. Under theseconditions 7.5 mole per cent of the acid evolved as HF. Analysis of thereaction products after removal of the catalyst showed a conversion of26%.

Example VIII CHClFz (B. P. 40.8 C.) was treated in a manner similar tothat described in Example I, the flow rate being maintained at about 57g./hr. and the temperature at about 700 C. A conversion of 49% wasobtained as compared with a conversion of 27% at the higher flow rateused in Example I.

Example IX Provision was made to operate the apparatus described inExample I at an absolute pressure of 0.5 atm. CHClFz (B. P. 40.8 C.) waspassed through the tube at a rate of about 35 g./hr. and a temperatureof about 700 C. The reaction products were washed with water, dried andcondensed in receivers cooled to about and C., respectively. Acidanalysis showed a conversion of 50%. The composition of the crude was asfollows:

Amount Present, Volume Per Cent Component CzFi CHCIF: Material boilingabove 40 C A 02F; yield of 89% was obtained.

Example X CHC1F2 recovered from a previous pyrolysis was treated in amanner similar to that described in Example I. The temperature wasmaintained at about 700 C. and the conversion at about 26%. The isolatedyield of C2F4 from the pyrolysis products was found to be 89% of theory.The converted material was found to contain 96 volume per cent of C2F4.

Example XI In a large scale pyrolysis of CHClFz under conditions similarto that used in Example I, a large amount of material boiling above -40C. was obtained. The following are among the compounds which wereisolated and identified. Some of their physical constants are given.

. Compound M01. Wt.

B. Pt. Density nD Cale. Found HCsFwCI- HCqFnCL HC F CL dfi=L 661ai=1.7as

d=1. 77s d=1.s1 solid at room temperature. M. Pt. 52 0 lilss umes PV= RTwhich for compounds of this type gives a M. W. from 2 to 4% g 1Calculated. v

' 'The material, boiling over -40 C., also con tained higher boilingmembers of the series H(CF2) 11.01, probably including those wherein nis 15 to 20, but the amounts obtained were insuffici'ent to permitaccurate identification. Several constant boiling mixtures were alsofound in the pyrolysis material; one of them boiled at about 12 C. andcontained about 80 vol. per cent of C2HC1F4; together with a componentwhich boiled at '4 C. and had a molecular weight of about 202. Anotherazeotrope boiled at about 8 to 9 C. and contained about 90 vol. per centof CHClzF. A third constant boiling mixture had a boiling point of 4Example XII The pyrolysis of CHClFz was carried out in a platinum-linedInconel-jacketed nickel tube, 13.7 mm. ID. X 108 cm. The reactionproducts were washed with water, dried and condensed in two receivers.ne pyrolysis was carried out at 30%, 77% and 100% conversions and theproportion of the various fractions in the high boilers determined bydistillation. These results are summarized as follows:

various conditions of temperature, pressure and conversion are given inthe table:

Pyrolysis of CHCIF: Under Pressure N i s. m.

Abs. Pyr oysis, ggggg l gp r e egl i t I Sioll Boilers" 1 1 The percentfhigh boilers is based on the amount of CHClF which d sappeared in thereaction by pyrolysis.

The above table shows'that an increase in pressure generally results inthe increase of the percentage of high boilers obtained in thepyrolysis. Although the composition of these products varied in eachrun, over a boiling range of 12 to over 190 C., over 65% of the highboilers were H(CF2)3C1 and H(CF2)4Cl.

1 This value is the ratio of amount of H. B. obtained to the totalCHClFz passed through the pyrolysis tube.

Erample XIII CHClF2 was passed through a nickel-jacketed carbon tube,18.8 mm. ID. x 600 mm. long at a rate of 82 g. per hour. The temperaturewas maintained at about 700 C. and the conversion at about 24%. A coilof gold wire was then placed in the center of the heated zone and thepyrolysis continued for five hours in the presence of the test piece.The conversion and the HF splitoff remained the same and no change wasnoticed in the composition of pyrolysis products. The corrosion rate onthis test piece was found to be less than 0.1 X 10 inches per monthpenetration. This rate is of the same order of magnitude as that forplatinum used under similar conditions for the pyrolysis of CHClFz.

Example XIV A platinum-lined, Inconel-jacketed nickel tube, 42" x 0.5"ID. was used in the pressure pyrolysis of CHClFz. The pyrolysistemperature was maintained over an estimated length of 20 cm. byelectrical heating. The desired pressure and conversion were maintainedby control of the temperature and flow of the organic material. Thereaction products were then washed, dried and condensed in receiverscooled in carbonice-acetone baths. No attempts were made to collect anyof the gases passing through the carboniceacetone traps. The liquidcondensates were then Example XV Example XVI CF3CH2C1 was passed througha platinum-lined Inconel-jacketed nickel tube, 13.7 mm. I. D. x 108 cm.,at a rate of about 110 g. per hour while the temperature in the tube waskept at about 615 C.

distilled in a laboratory helices-packed column I and the amount ofCI-IClFz destroyed by the process thus determined. 7

The results of the pyrolysis of CHC1F2 under over an estimated length of200 mm. by electrical heating. The reaction products were .washed withwater, dried and condensed. Acid analysis showed a conversion of about52%. The following compounds were isolated and identified in theproduct:

CI-IF's (B. P. 8l C.) with a vapor density of 2.217 g. per liter at 22C. and 59 0 mm.

C3H3F5 (B. P. 19.6) with a vapor density of 5.06 g. per liter at 27 C.and 760 mm.

C LHBClFG (B. P. 35-36") with a vapor density of 5.272 g. per liter at24 C. and 480 mm.

Example XVII CHClzF was passed through a platinum-lined tube similar tothat described in Example I at a.

rate of 121 g. per hour and with a tube temperature of about 675 C.

Dichlorodifiuoroethylene (C2C12F2), B. P. 21- 22 C., C2CI4F2, B. P.92-93 C., and C3H2C13F3, B. P. 108 C., were isolated and identified inthe product.

Example XVIII CHsCClFz was passed through a platinumlinedInconel-jacketed nickel tube, 13.7 mm. I. D. x 108 cm. long, at a rateof about 120 g. per hour. The tube temperature was maintained at 715 C.over an estimated length of 200 mm. by electrical heating. The reactionproducts were washed with water, dried and condensed in two receivers.The first receiver was cooled to about 70 C. while the second receiverwas cooled in a bath of liquid nitrogen. Acid analysis of the wash watershowed a conversion of about 50%. The pyrolysis of this hydrocarbonproceeded smoothly to the formation of substantially pure CH2CF2. Theboiling point of this material is 82 C., and its vapor density at 28 C.and 756 mm. was 2.58 g. per liter.

Example XIX CHF2CC1F2 Example XX About 5 g. per hour of CH2=CC1F (B. P.-27) was passed through a platinum-lined Inconeljacketed nickel tube,13.7 mm. I. D. x 108 cm. The temperature range covered was from 780 to930 C. The reaction products were washed with water, dried and condensedin two receivers. This crude reaction product had a boiling range of 30to +20 C. with definite fractions boiling at about C. and 20 C.

Example XXI H(CF2)3C1 (B. P. 21 C.) was passed through a platinum-linedInconel-jacketed nickel tube, 13.7 mm. I. D. x 108 cm., the flow ratebeing maintained at about 118 g. per hour and the temperature at about780 C. Acid analysis showeda conversion of about 46%. A total of about189 g. of crude organic products were collected. The following compoundswere isolated and identified in the pyrolysis products: C2F4 and CClzFzwhich have boiling points of -76 C. and 30 C., re-

spectively. Another fraction boiling at 12 C.

with an M. W. of 164 was obtained which was an azeotropic mixture ofC4Fa (octafluorocyclobutane) and CHF2CC1F2.

Example XXII In the pyrolysis of CHClF'z to C2F4 there was obtained somereaction products Whose boiling range was from 12 C. to about 250 C.This fraction, designated the high boilers and which was a mixture ofthe compounds having the formula -H(CF2)1LC1 was subjected to pyrolysisat 740 C. in a platinum-lined Inconel-jacketed nickel tube, 13.7 mm. I.D. x 108 cm. with the conversion at about 40%. The recovered materialwas washed, dried and fractionated; The fraction boiling above 12 C. wasthen subjected to a second pyrolytic treatment under similar conditionsas in the first. Although the temperature of the tube was, raised to 840C. the conversion remained fairly constant at 20%. After Washing anddrying, the pyrolysis material was again fractionated. The successivepyrolyses of the high boilers did not result in the intended building upof carbon chains. Instead there was a definite breakdown in the moleculeto produce a mixture, containing the same compounds as the startingmixture but with an increase in the proportion of the lower boilingmembers. The composition of the original high boilers and those of thepyrolyzed materials was as follows:

Percentage composition based on total high boilers.

Example XXIII CC12F2 was passed through a platinum-linedInconel-jacketed nickel tube, 19 mm. I. D. x 60'-' long at a rate ofabout 23 g. per hour. The sur;- face temperature was maintained at about950 970 C. over an estimated length of 200 mm. by electrical heating.The reaction products were washed with sodium sulfite solution, driedand condensed in receivers cooled to 76 C. followed by a tailingreceiver cooled in liquid nitrogen. About 3 g. of CE; was foundin theliquid nitrogen trap. This material had a boiling point of 129 C. and amolecular weight (vapor density method) of 90. (Calculated for CF 1,88.) The 76 condensate, totalling about 66 g., was distilled and thefollowing compounds isolated: about 7 g. of CF3C1, boiling point 81,also about 1.5 g. of fraction boiling above 40 C. which was notidentified. The rest of the condensate was the original startingmaterial, CC12F2 boiling at -29 to -30 C. Analysis of the Wash watershowed the presence of HF, I-ICl and free chlorine;

Example XXIV CClF'zCClFz was pyrolyzed in a platinum-lined tube similarto that described in Example XXIII at a tube temperature of about 880 C.About 170 g. of material was passed through in 1.25 hours at a contacttime approximating 2-3 seconds. Extensive decomposition was evident andfree chlorine was detected. The reaction products were washed free ofacid constituents, dried and fractionated. About g. of CF3C1 and about12 g. of CF2C12 were isolated and identified. High boiling constituents(boiling above 4 C.) were obtainedbut were not identified.

The reaction products may be washed with water or alkaline solution toremove acid constituents before condensation and analysis, although thisis not necessary. In some cases, it is advantageous to separate certaindesired components before acid removal. 1

The process produces both saturated and unsaturated products. A veryimportant olefine which is efiiciently produced by the process is .CFzcFc, which is a valuable intermediate for refrigerants and plastics.Among'the saturated compounds which are produced are mono carbonfluorides, such as CCIF3, and fluorides having a served that theproducts tend to increase .in stability as they approachsaturation byfluorine; for example, the compound =CI-IF3 is very stable; in severalcases the substitution of fluorine for chlorine has produced a decreasein the reactivity of the compound. Because of this, the process is aparticularly satisfactory method of producing reactions of the typedescribed among fluoro compounds containing chlorine.

The compounds of the series H(CF2)12C1 where .in n is at least 3 are newand valuable compounds. They are very much more stable to heat andchemical reagents than the next lower homologue whereby they may beemployed under conditions, "such as reaction media, heat transfer mediaand the like, where the next lower homologue would not be practical. Forexample, when TH CCFzJ 2C1 is heated to 150 C. under pressure with 1.5moles of alcoholic potassium hydroxide for hours, part of the materialwas dehydrochlorina'ted to CF2=CF2 and other products. When each ofH'(CF2) 4C1, H(CF2 5C]. and HKCFzlsCl were treated in the same "mannerat temperatures as high as 175C, no dehydrochlorina'tion took place.Also, when H(CF2) 201 was heated with1l2 moles of zinc dust in an excessof absolute methyl alcohol "for 5 hours at 150 C. under pressure,chlorine and fluorine were split out to produce 'CHFzCFz. When each ofHi-CFzMCl, I-I(-CF2-) 4C1, H'(CF2-) 5C1 and II(CF2) 601 were treated inthe same manner at temperatures up'to 170 'C., no detectable amounts ofthe corresponding'olefine were obtained.

The particular advantage of the invention is that a 'pyrolytic processhas been discover'ed'for the production of new compounds and for :themore efii'cien't production of old compounds, which is characterized byits simplicity and the ease with which it ma be operated. The inventionprovides an efficient method of producing organic com-pounds containingfluorine, particu- :larly fiuorinate-d olefines. These-compounds haveuses in themselves, such as for refrigerants, anaesthetics, and solventsand are useful as intermediates for the production of alcohols, esters,halides, and .alkyl derivatives. A particular advantage of the inventionis that the process is most efficient for the production of the valuablecompound CFz=CFz, which is an intermediate of wide utility. Theinvention is 'also useful for the synthesis of compounds having morecarbon atoms than the'compound pyrol-yzed, and for the extension .ofcarbon chains. The process in volves the pyrolysis of compounds of bothlight and heavy .molecular weight. The pyrolysis has been carried out inboth .acontinuous and a stepwise .manner, and a large variety ofconditions has been employed, so that it :is beyond'question that theprocess is of generalapplication.

.As :many apparently widely different embodiments of this invention maybe .made without 12 departing from the spirit and scope thereof, it isto be understood that we do not limit ourselves to the specificembodiments thereof except as defined in the appended claims.

We claim:

1. The process of converting fluoro-chloroalkanes to different fluorinecontaining organic compounds which comprises pyrolyzing afluoroc'hloro-alkane of from 1 to 3 carbon atoms containing at least onehydrogen atom and in which each carbon carrying a flourine atom alsocarries at least one additional halogen atom of the group consisting ofchlorine and fluorine, at a temperature between 600 C. and 1000 C.

2. The process of converting fluoro-chloroalkanes to different fluorinecontaining organic compounds which comprises pyrolyzing afluorochloro-alkane of from 1 to 3 carbon atoms containing both ahydrogen atom and .a chlorine atom on a single carbon atom and in whicheach carbon carrying a fluorine atom also carries at least oneadditional halogen atom of the group consisting of chlorine andfluorine, at a temperature between 600 C. and 1000 C.

3. The process of converting fluoro-chloroalkanes to different fluorinecontaining organic compounds which comprises pyrolyzing afluoroch'loro-alkane of from '1 to 3 carbon atoms containing a hydrogenatom and a chlorine atom on adjacent carbon atoms and in which eachcarbon carrying a fluorine atom also carries at least one additionalhalogen atom of the group consisting of chlorine and fluorine, .at .atemperature between 600 C. and 1000 C.

4. The process of producing the compound represented vby the formulaCF2=CF2 which comprises pyrolyzing the compound represented by theformula CHClFz.

5. The process of producing the compound represented by the formulaCF2=CF2 which comprises pyrolyzing the compound represented by theformula CHClFz under pressures between 0.1 and 10 atmosphere absolute.

6. The process of producing the compound represented by the .formulaCE2=CF2 which comprises pyrolyzing the compound represented by theformula CHClFz at a temperature between 600 C. and 1000 F. atatmospheric pressure.

'7. The process of producing .the compound represented by the formulaCF2=CF2 which comprises heating the compound represented by the formulaCHClFz at a temperature of about 700 C. in a platinum reaction vessel,condensing the product, and separating its constituents.

8. The process which comprises pyrolyzing CHClFz by passing it throughanoble metal tube heated to a temperature of about 700 0., washing thereaction products with water, drying the reaction products, condensingthem, and subjecting them to fractional distillation.

9. The process which comprises pyrolyzing CHClFz by passing it through anoble metal tube at a temperature of about 700 C. ata pressure of aboutfour atms. absolute, washing the product with water, drying it,condensing it, and isolating its constituents by fractionaldistillation.

10. The process of producing the compound represented by the formulaCH2=CF2 which comprises heating CH3CC1F2 .at temperature of from about600 .C. to about 1000 C. for suficient time .to convert a substantialportion of the CH3CC1F2 t0 CH2=CF2.

11. The process of producing the compound represented by the formulaC2F4 which comprises heating CC1F2CI-IF2 at temperature of from about600 C. to about 1000 C. for sufiicient time to convert a substantialportion of the CC1F2CI-IF2 to 02R; and other products.

12. A compound represented by the formula:

mcFmci in which n is an integer of from 3 to 14.

13. The compound represented by the formula:

FREDERICK B. DOWNING. ANTHONY F. BENNING. ROBERT C. MOHARNESS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Swaney et a1. May 15, 1945 Henne et a1: J. A. C.8., vol. 58, pages 402-3 Senderens: Bull. Soc. Chem. de France, 4thSeries, v01. 3,- pages 823-829 (1908).

Fieser and Fieser: Organic Chemistry (1944) page 32.

Gilman: Organic Chemistry (2nd ed. 1943), vol. I, pages 956; 959 to 961.

Henne etaL: J. Am. Chem. Soc., vol. 58, pages 882-884 (1936).

Ruff et a1.:'-Zeit. fiir anorg. und allgemeine Chemie, vol. 201, 256-7(1931).

Nuckols et a1.: Chem. Abs., vol. 28, 2079 (1934)

1. THE PROCESS OF CONVERTING FLUORO-CHLOROALKANES TO DIFFERENT FLUORINECONTAINING ORGANIC COMPOUNDS WHICH COMPRISES PYROLYZING AFLUOROCHLORO-ALKANE OF FROM 1 TO 3 CARBON ATOMS CONTAINING AT LEAST ONEHYDROGEN ATOM AND IN WHICH EACH CARBON CARRYING A FLOURINE ATOM ALSOCARRIES AT LEAST ONE ADDITIONAL HALOGEN ATOM OF THE GROUP CONSISTING OFCHLORINE AND FLUORINE, AT A TEMPERATURE BETWEEN 600* C. AND 1000* C.